We're the (humbled) owners of a 2011 Class B Mercedes with an inbuilt ECO start/stop system. As far as I understand this is how it's supposed to work:

Gear in neutral.

Press the brake pedal all the way.

Motor turns "off".

Shift into first gear.

Motor turns back on.

The salesman remarked that the main problem people have with this system is they don't actually press the pedal all the way to the metal. However, we're experiencing that while this system just works at times, it also just doesn't work at other times. More specifically, it tends to work when leaving home and not to work in return trips.

The operating manual is in German since this is a used car, so I'm kind of at a loss. What's going on here?

They make the manuals in English, depending on your dealer/mech they may give you one; my mom asked and got one (a $200 book) by asking, and that was a 7 year old model at the time. I'd check my manual but the 2006 E class doesn't have this feature
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Ben BrockaJun 24 '12 at 3:17

my vacuum failed under stop start an i had an accident at very low speed.. the engine didnt start then..
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user3055Apr 22 '13 at 12:14

@badp Vacuum is used to control things like the HVAC vents, power brakes, various valves and switches used for emission and engine controls. Vacuum is created by the engine running and there is usually a vacuum reservoir that keeps some in reserve to continue to provide vacuum in times of low engine vacuum (IE acceleration) or when the engine is off. When there is not enough vacuum to keep those things working it keeps the engine running until enough vacuum is present
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Move more comments link to top♦Jun 21 '12 at 19:10